 
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <linux/kd.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <string.h>
#include <errno.h>

struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
char *frameBuffer = 0;

//打印fb驱动中fix结构信息，注：在fb驱动加载后，fix结构不可被修改。
void
printFixedInfo ()
{
    printf ("Fixed screen info:\n"
            "\tid: %s\n"
            "\tsmem_start: 0x%lx\n"
            "\tsmem_len: %d\n"
            "\ttype: %d\n"
            "\ttype_aux: %d\n"
            "\tvisual: %d\n"
            "\txpanstep: %d\n"
            "\typanstep: %d\n"
            "\tywrapstep: %d\n"
            "\tline_length: %d\n"
            "\tmmio_start: 0x%lx\n"
            "\tmmio_len: %d\n"
            "\taccel: %d\n"
            "\n",
            finfo.id, finfo.smem_start, finfo.smem_len, finfo.type,
            finfo.type_aux, finfo.visual, finfo.xpanstep, finfo.ypanstep,
            finfo.ywrapstep, finfo.line_length, finfo.mmio_start,
            finfo.mmio_len, finfo.accel);
}

//打印fb驱动中var结构信息，注：fb驱动加载后，var结构可根据实际需要被重置
void
printVariableInfo ()
{
    printf ("Variable screen info:\n"
            "\txres: %d\n"
            "\tyres: %d\n"
            "\txres_virtual: %d\n"
            "\tyres_virtual: %d\n"
            "\tyoffset: %d\n"
            "\txoffset: %d\n"
            "\tbits_per_pixel: %d\n"
            "\tgrayscale: %d\n"
            "\tred: offset: %2d, length: %2d, msb_right: %2d\n"
            "\tgreen: offset: %2d, length: %2d, msb_right: %2d\n"
            "\tblue: offset: %2d, length: %2d, msb_right: %2d\n"
            "\ttransp: offset: %2d, length: %2d, msb_right: %2d\n"
            "\tnonstd: %d\n"
            "\tactivate: %d\n"
            "\theight: %d\n"
            "\twidth: %d\n"
            "\taccel_flags: 0x%x\n"
            "\tpixclock: %d\n"
            "\tleft_margin: %d\n"
            "\tright_margin: %d\n"
            "\tupper_margin: %d\n"
            "\tlower_margin: %d\n"
            "\thsync_len: %d\n"
            "\tvsync_len: %d\n"
            "\tsync: %d\n"
            "\tvmode: %d\n"
            "\n",
            vinfo.xres, vinfo.yres, vinfo.xres_virtual, vinfo.yres_virtual,
            vinfo.xoffset, vinfo.yoffset, vinfo.bits_per_pixel,
            vinfo.grayscale, vinfo.red.offset, vinfo.red.length,
            vinfo.red.msb_right, vinfo.green.offset, vinfo.green.length,
            vinfo.green.msb_right, vinfo.blue.offset, vinfo.blue.length,
            vinfo.blue.msb_right, vinfo.transp.offset, vinfo.transp.length,
            vinfo.transp.msb_right, vinfo.nonstd, vinfo.activate,
            vinfo.height, vinfo.width, vinfo.accel_flags, vinfo.pixclock,
            vinfo.left_margin, vinfo.right_margin, vinfo.upper_margin,
            vinfo.lower_margin, vinfo.hsync_len, vinfo.vsync_len,
            vinfo.sync, vinfo.vmode);
}

//画大小为width*height的同色矩阵，8alpha+8reds+8greens+8blues
void
drawRect_rgb32 (int x0, int y0, int width, int height, int color)
{
    const int bytesPerPixel = 4;
    const int stride = finfo.line_length / bytesPerPixel;

    int *dest = (int *) (frameBuffer)
        + (y0 + vinfo.yoffset) * stride + (x0 + vinfo.xoffset);

    int x, y;
    for (y = 0; y < height; ++y)
    {
        for (x = 0; x < width; ++x)
        {
            dest[x] = color;
        }
        dest += stride;
    }
}

//画大小为width*height的同色矩阵，5reds+6greens+5blues
void
drawRect_rgb16 (int x0, int y0, int width, int height, int color)
{
    const int bytesPerPixel = 2;
    const int stride = finfo.line_length / bytesPerPixel;
    const int red = (color & 0xff0000) >> (16 + 3);
    const int green = (color & 0xff00) >> (8 + 2);
    const int blue = (color & 0xff) >> 3;
    const short color16 = blue | (green << 5) | (red << (5 + 6));

    short *dest = (short *) (frameBuffer)
        + (y0 + vinfo.yoffset) * stride + (x0 + vinfo.xoffset);

    int x, y;
    for (y = 0; y < height; ++y)
    {
        for (x = 0; x < width; ++x)
        {
            dest[x] = color16;
        }
        dest += stride;
    }
}

//画大小为width*height的同色矩阵，5reds+5greens+5blues
void
drawRect_rgb15 (int x0, int y0, int width, int height, int color)
{
    const int bytesPerPixel = 2;
    const int stride = finfo.line_length / bytesPerPixel;
    const int red = (color & 0xff0000) >> (16 + 3);
    const int green = (color & 0xff00) >> (8 + 3);
    const int blue = (color & 0xff) >> 3;
    const short color15 = blue | (green << 5) | (red << (5 + 5)) | 0x8000;

    short *dest = (short *) (frameBuffer)
        + (y0 + vinfo.yoffset) * stride + (x0 + vinfo.xoffset);

    int x, y;
    for (y = 0; y < height; ++y)
    {
        for (x = 0; x < width; ++x)
        {
            dest[x] = color15;
        }
        dest += stride;
    }
}

void
drawRect (int x0, int y0, int width, int height, int color)
{
    switch (vinfo.bits_per_pixel)
    {
    case 32:
        drawRect_rgb32 (x0, y0, width, height, color);
        break;
    case 16:
        drawRect_rgb16 (x0, y0, width, height, color);
        break;
    case 15:
        drawRect_rgb15 (x0, y0, width, height, color);
        break;
    default:
        printf ("Warning: drawRect() not implemented for color depth %i\n",
                vinfo.bits_per_pixel);
        break;
    }
}

#define PERFORMANCE_RUN_COUNT 5
void
performSpeedTest (void *fb, int fbSize)
{
    int i, j, run;
    struct timeval startTime, endTime;
    unsigned long long results[PERFORMANCE_RUN_COUNT];
    unsigned long long average;
    unsigned int *testImage;

    unsigned int randData[17] = {
        0x3A428472, 0x724B84D3, 0x26B898AB, 0x7D980E3C, 0x5345A084,
        0x6779B66B, 0x791EE4B4, 0x6E8EE3CC, 0x63AF504A, 0x18A21B33,
        0x0E26EB73, 0x022F708E, 0x1740F3B0, 0x7E2C699D, 0x0E8A570B,
        0x5F2C22FB, 0x6A742130
    };

    printf ("Frame Buffer Performance test...\n");
    for (run = 0; run < PERFORMANCE_RUN_COUNT; ++run)
    {
        /* Generate test image with random(ish) data: */
        testImage = (unsigned int *) malloc (fbSize);
        j = run;
        for (i = 0; i < (int) (fbSize / sizeof (int)); ++i)
        {
            testImage[i] = randData[j];
            j++;
            if (j >= 17)
                j = 0;
        }

        gettimeofday (&startTime, NULL);
        memcpy (fb, testImage, fbSize);
        gettimeofday (&endTime, NULL);

        long secsDiff = endTime.tv_sec - startTime.tv_sec;
        results[run] =
            secsDiff * 1000000 + (endTime.tv_usec - startTime.tv_usec);

        free (testImage);
    }

    average = 0;
    for (i = 0; i < PERFORMANCE_RUN_COUNT; ++i)
        average += results[i];
    average = average / PERFORMANCE_RUN_COUNT;

    printf (" Average: %llu usecs\n", average);
    printf (" Bandwidth: %.03f MByte/Sec\n",
            (fbSize / 1048576.0) / ((double) average / 1000000.0));
    printf (" Max. FPS: %.03f fps\n\n",
            1000000.0 / (double) average);

    /* Clear the framebuffer back to black again: */
    memset (fb, 0, fbSize);
}

int
main (int argc, char **argv)
{
    const char *devfile = "/dev/fb0";
    long int screensize = 0;
    int fbFd = 0;


    /* Open the file for reading and writing */
    fbFd = open (devfile, O_RDWR);
    if (fbFd == -1)
    {
        perror ("Error: cannot open framebuffer device");
        exit (1);
    }

    //获取finfo信息并显示
    if (ioctl (fbFd, FBIOGET_FSCREENINFO, &finfo) == -1)
    {
        perror ("Error reading fixed information");
        exit (2);
    }
    printFixedInfo ();
    //获取vinfo信息并显示
    if (ioctl (fbFd, FBIOGET_VSCREENINFO, &vinfo) == -1)
    {
        perror ("Error reading variable information");
        exit (3);
    }
    printVariableInfo ();

    /* Figure out the size of the screen in bytes */
    screensize = finfo.smem_len;

    /* Map the device to memory */
    frameBuffer =
        (char *) mmap (0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
                     fbFd, 0);
    if (frameBuffer == MAP_FAILED)
    {
        perror ("Error: Failed to map framebuffer device to memory");
        exit (4);
    }

    //测试virt fb的性能
    performSpeedTest (frameBuffer, screensize);

    printf ("Will draw 3 rectangles on the screen,\n"
            "they should be colored red, green and blue (in that order).\n");
    drawRect (vinfo.xres / 8, vinfo.yres / 8,
             vinfo.xres / 4, vinfo.yres / 4, 0xffff0000);
    drawRect (vinfo.xres * 3 / 8, vinfo.yres * 3 / 8,
             vinfo.xres / 4, vinfo.yres / 4, 0xff00ff00);
    drawRect (vinfo.xres * 5 / 8, vinfo.yres * 5 / 8,
             vinfo.xres / 4, vinfo.yres / 4, 0xff0000ff);

    sleep (10);
    printf (" Done.\n");

    munmap (frameBuffer, screensize);    //解除内存映射，与mmap对应

    close (fbFd);
    return 0;
}
